Grain refiner, aluminum material, preparation method and application

Abstract

The invention discloses a grain refiner, an aluminum material, a preparation method and application. The preparation method of the grain refiner comprises the following steps: (1) adding rare earth oxide and carbon-containing alumina powder into a salt solvent melt, and stirring to prepare a liquid-solid mixture; cooling the liquid-solid mixture to obtain a precursor; (2) forming an aluminum melt from an aluminum ingot; (2) adding potassium fluotitanate and potassium fluoborate into the aluminum melt, stirring, then adding the precursor obtained in the step (1), continuously stirring and reacting until the reaction is complete, and removing the salt solvent melt to obtain an alloy solution; and (3) the alloy solution is subjected to refining degassing and slagging-off in sequence, an alloy solution obtained after slagging-off is obtained, the alloy solution obtained after slagging-off is formed, and the grain refiner is obtained. The grain refiner provided by the invention has the advantages of fine size of a refined phase, dispersed distribution and uniform components.

Description

Technical Field

[0001] The invention relates to a grain refiner, an aluminum material, a preparation method and an application thereof. Background Art

[0002] Grain refinement of aluminum alloys can obtain dense alloy structures, and can also reduce the tendency of hot cracking and segregation of castings, reduce porosity, and thus improve the comprehensive performance of the alloy. At present, the most commonly used and effective refinement method is to add grain refiners. However, the commonly used aluminum alloy refiner - aluminum titanium boron refiner, due to the easy agglomeration of the refinement phase TiB2, greatly reduces its refinement effect and refinement duration. In addition, the refinement effect of aluminum titanium boron refiner is significantly reduced when refining high silicon aluminum alloy (Si≥3.0wt.%), which is called "Si poisoning" of refiner. Aluminum titanium carbon has the advantages of finer TiC refinement phase, uniform distribution and not easy to aggregate, and good coherence relationship with Al. The refinement effect is better than that of traditional aluminum titanium boron refiner, and it has received extensive attention and application. However, due to the poor wettability of C in Al, it is very difficult to prepare. The preparation cost of aluminum titanium carbon grain refiner is high by strong stirring or high temperature reaction, which limits the wide application of aluminum titanium carbon grain refiner.

[0003] In recent years, researchers have devoted themselves to developing new refiners to solve the above problems. For example, CN1108277374A, CN102784905B, CN111363936A and CN114150173A respectively disclose the preparation methods of Al-Ti-CY, Al-Ti-C-Er, Al-Ti-C-La and Al-Ti-C-Sc grain refiners, wherein the carbon source is graphite powder or carbon powder. Since C and Al have poor wettability, C is difficult to penetrate, and the temperature is high, and the preparation cost is also high. CN100467635C discloses a preparation method of aluminum-titanium-carbon master alloy, which uses aluminum-carbon and aluminum-titanium alloy as raw materials, has a simple process, but high cost and large size of refined phase. CN112899512B discloses an aluminum-titanium-carbon alloy grain refiner and its preparation method, which uses nano-scale TiC as a carbon source, which is costly, and the wettability between the added particles of TiC and Al is poor, making it difficult to ensure the uniform distribution of TiC in the Al melt. CN111996424B discloses a TCB-Al seed alloy, its manufacturing method and a heritable aluminum alloy, which uses Al-Al3BC master alloy as a carbon source, first prepares the master alloy by a powder metallurgy method, and then adds it to pure aluminum as a carbon source. However, this method has a long process and high cost.

[0004] CN118241081A discloses an aluminum-titanium-carbon-boron-cerium grain refiner, a preparation method and its application. The refiner of the invention is composed of the following components: 3-5% titanium, 0.2-0.4% boron, 0.1-0.3% carbon, 2-6% cerium, the sum of other impurities ≤0.15%, and the balance is aluminum; the preparation method comprises the following steps: aluminum powder, graphite powder and potassium fluoride are made into mixed powder, which is divided into two parts; aluminum-cerium master alloy is added into aluminum melt, after reaction, slag is removed, the temperature is raised to 1000-1200°C, and then the mixed powder is added in batches at intervals; after the reaction is completed, the temperature is lowered to 800-900°C, and aluminum-boron master alloy is added to continue the reaction; a solvent is added for stirring and refining, and the solvent is a mixture of potassium chloride, magnesium nitrate, sodium chloride and calcium nitrate in a mass ratio of (5-10): (10-25): (1-3): (0.2-0.3); after refining and heat preservation, casting is performed to obtain the aluminum-titanium-carbon-boron-cerium grain refiner. The invention uses graphite powder as the carbon source and aluminum-boron intermediate alloy, which makes it difficult for C to penetrate, and the temperature is high and the preparation cost is also high. Summary of the invention

[0005] In view of this, one object of the present invention is to provide a method for preparing a grain refiner, which has good process repeatability, a simple way of introducing a carbon source, and is easier to enter into an aluminum melt. Another object of the present invention is to provide a grain refiner, whose refined phase has a small size, a dispersed distribution, and a uniform composition. Another object of the present invention is to provide a method for preparing an aluminum material. Another object of the present invention is to provide an aluminum material. Still another object of the present invention is to provide a use of a grain refiner.

[0006] In one aspect, the present invention provides a method for preparing a grain refiner, comprising the following steps:

[0007] (1) adding 10 to 60 parts by weight of rare earth oxide and 5 to 30 parts by weight of carbon-containing aluminum oxide powder to 30 to 80 parts by weight of a salt solvent melt, stirring to form a liquid-solid mixture; cooling the liquid-solid mixture to obtain a precursor;

[0008] (2) 900 to 1000 parts by weight of an aluminum ingot is formed into an aluminum melt; 150 to 250 parts by weight of potassium fluorotitanate and 40 to 70 parts by weight of potassium fluoroborate are added to the aluminum melt and stirred, and then 20 to 50 parts by weight of the precursor obtained in step (1) are added, and the reaction is continued to be stirred until the reaction is complete, and the salt solvent melt is removed to obtain an alloy solution;

[0009] (3) The alloy solution is refined, degassed and deslagging is performed in sequence to obtain a deslagging alloy solution, and the deslagging alloy solution is molded to obtain a grain refiner.

[0010] According to the preparation method of the present invention, preferably, the rare earth element in the rare earth oxide is selected from one or more of lanthanum, cerium, yttrium, erbium and scandium.

[0011] According to the preparation method of the present invention, preferably, the salt solvent melt is prepared by heating cryolite, sodium chloride and potassium chloride; wherein, based on the mass of the salt solvent melt, the content of cryolite is 65-85wt%, the content of sodium chloride is 8-15wt%, and the content of potassium chloride is 10-15wt%.

[0012] According to the preparation method of the present invention, preferably, aluminum citrate is placed in a vacuum of 10 -2 The mixture is heated to 750-850°C at 8-15°C / min under a temperature of 1000-2000°C and kept at this temperature for 20-60 minutes to form carbon-containing alumina powder.

[0013] According to the preparation method of the present invention, preferably, the alloy nucleation particle phase of the grain refiner includes TiAl3 phase, C-doped TiB2, B-doped TiC phase and Ti2Al 20 One or more RE phases, the matrix phase is α-Al phase.

[0014] According to the preparation method of the present invention, preferably, the size of the TiAl3 phase is less than or equal to 20 μm; the size of the C-doped TiB2 phase is less than or equal to 1 μm, the size of the B-doped TiC phase is less than or equal to 1 μm, and the size of the Ti2Al 20 The size of the RE phase is less than or equal to 10 μm.

[0015] In another aspect, the present invention also provides a grain refiner prepared according to the method as described above.

[0016] In another aspect, the present invention further provides a method for preparing an aluminum material, comprising the following steps:

[0017] Melting aluminum raw material or aluminum-silicon alloy to obtain a melt; adding the grain refiner as described above to the melt to obtain a molten metal; refining, degassing, and slagging the molten metal, then cooling it, and then performing a solidification and molding process to obtain an aluminum material;

[0018] Wherein, the addition amount of the grain refiner is 0.05-0.6% of the melt mass.

[0019] In another aspect, the present invention further provides an aluminum material, which is prepared by the preparation method as described above.

[0020] In yet another aspect, the present invention provides a use of the grain refiner as described above in refining the grain size of aluminum or its alloy.

[0021] The grain refiner of the present invention refines the phase with small size, dispersed distribution and uniform composition. The preparation method of the grain refiner of the present invention has high effective element yield, has better refinement effect than the grain refiner prepared by the prior art process, has simple preparation process and lower preparation cost. The preparation method of the present invention is to generate C-doped TiB2 phase and B-doped TiC phase, TiAl3 phase and Ti2Al 20 The RE phase method uses calcined aluminum citrate as a carbon source, and carbon is more easily incorporated into the aluminum liquid. Rare earth is added in the form of oxides and has a lower cost. C-doped TiB2 phase can reduce the size of the refined phase TiB2, reduce its growth and agglomeration tendency, and inhibit the "Si poisoning" phenomenon of the refiner; B-doped TiC can prevent TiC from growing and enhance the heterogeneous nucleation ability of the refined phase TiC; rare earth purifies the refiner alloy, and forms rare earth compounds with Al and other impurities, which can also act as nucleation points for α-Al and play a refining role. The grain refiner prepared by the present invention has many types of effective nucleation points, a large number density, and a high refining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The XRD diagrams of Examples 1 and 2 are shown in FIG.

[0023] Figure 2a This is the TiB2 phase microstructure diagram of the C-doped TiB2 phase in the Al-Ti-BC-LaCe grain refiner of Example 1.

[0024] Figure 2b This is the element distribution diagram of the C-doped TiB2 phase in the Al-Ti-BC-LaCe grain refiner of Example 1.

[0025] Figure 2c for Figure 2b A partial enlarged view of .

[0026] Figure 3a This is the morphology of the B-doped TiC phase in the Al-Ti-BC-LaCe grain refiner of Example 1.

[0027] Figure 3b This is the element distribution diagram of B-doped TiC phase in the Al-Ti-BC-LaCe grain refiner of Example 1.

[0028] Figure 3c for Figure 3b A partial enlarged view of .

[0029] Figure 4 This is the SEM scanning electron microscope image of Example 1.

[0030] Figure 5The metallographic structure diagrams of the aluminum raw material, the refined aluminum obtained in Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 4 and Comparative Experimental Example 1 are measured.

[0031] Figure 6 This is the metallographic structure diagram of the aluminum-silicon alloy of Experimental Example 5. Figure 6 a is the metallographic structure diagram before refinement. Figure 6 b is the metallographic structure diagram after refinement. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] <Method for preparing grain refiner>

[0034] The method for preparing the grain refiner of the present invention comprises the following steps: (1) preparing a precursor; (2) preparing an alloy solution; and (3) preparing the grain refiner.

[0035] Preparation of precursors

[0036] The present invention can use cryolite, sodium chloride and potassium chloride to form a salt solvent melt, and use the salt solvent melt as a solvent to form a precursor containing rare earth and carbon. This is conducive to the dispersion of rare earth and carbon, improves the efficiency of the reaction, and helps prevent the precipitation of refined phases.

[0037] Rare earth oxide and carbon-containing aluminum oxide powder are added into a salt solvent melt, mixed, and cooled to obtain a precursor.

[0038] The rare earth element in the rare earth oxide can be selected from one or more of lanthanum, cerium, yttrium, erbium, and scandium; preferably one or more of lanthanum, cerium, and yttrium; more preferably lanthanum and / or cerium. The mass of the rare earth oxide can be 10 to 60 parts by weight; preferably 15 to 50 parts by weight; more preferably 30 to 45 parts by weight.

[0039] In some embodiments, the rare earth oxide may be lanthanum oxide and cerium oxide, wherein the mass of lanthanum oxide may be 5 to 20 parts by weight, preferably 10 to 18 parts by weight, and more preferably 10 to 15 parts by weight. The mass of cerium oxide may be 5 to 40 parts by weight, preferably 15 to 35 parts by weight, and more preferably 20 to 30 parts by weight.

[0040] Aluminum citrate (C6H5AlO7) can be placed in a vacuum of 10 -2Pa to form alumina powder containing C. The calcination temperature may be 750-850°C, preferably 780-850°C, and more preferably 800-820°C. The heating rate may be 8-15°C / min, and preferably 10-13°C / min. The holding time may be 20-60min, preferably 25-50min, and more preferably 30-40min.

[0041] The amount of the carbon-containing aluminum oxide powder used may be 5 to 30 parts by weight, preferably 10 to 25 parts by weight, and more preferably 10 to 20 parts by weight.

[0042] The mass of the salt solvent melt can be 30 to 80 parts by weight, preferably 40 to 70 parts by weight, and more preferably 40 to 60 parts by weight. Based on the total weight of the salt solvent melt, cryolite is 65 to 85wt%, sodium chloride is 8 to 15wt%, and potassium chloride is 10 to 15wt%. Preferably, based on the total weight of the salt solvent melt, cryolite is 70 to 80wt%, sodium chloride is 10 to 15wt%, and potassium chloride is 11 to 14wt%. More preferably, based on the total weight of the salt solvent melt, cryolite is 72 to 75wt%, sodium chloride is 12 to 14wt%, and potassium chloride is 13 to 14wt%.

[0043] Preparation of alloy solution

[0044] The aluminum ingot is formed into an aluminum melt; potassium fluorotitanate and potassium fluoroborate are added into the aluminum melt and stirred, and then the obtained precursor is added, and the stirring reaction is continued until the reaction is complete, and the salt solvent melt is removed to obtain an alloy solution.

[0045] The mass of the aluminum melt may be 900 to 1000 parts by weight, preferably 920 to 980 parts by weight, and more preferably 940 to 960 parts by weight.

[0046] The mass of potassium fluorotitanate may be 150 to 250 parts by weight, preferably 160 to 230 parts by weight, and more preferably 170 to 200 parts by weight.

[0047] The mass of potassium fluoroborate may be 40 to 70 parts by weight, preferably 45 to 68 parts by weight, and more preferably 48 to 65 parts by weight.

[0048] The amount of the added precursor may be 20 to 50 parts by weight, preferably 25 to 48 parts by weight, and more preferably 27 to 46 parts by weight.

[0049] Preparation of grain refiner

[0050] The alloy solution is refined, degassed and deslagging in sequence to obtain a deslagging alloy solution; the deslagging alloy solution is molded to obtain a grain refiner.

[0051] In certain embodiments, the alloy solution after slagging can be cast into an ingot to obtain a grain refiner.

[0052] In other embodiments, the alloy solution after slagging can be cast into a cast rod and then extruded into a thin rod to obtain a grain refiner. The extrusion temperature can be 300-500° C., preferably 350-450° C., and more preferably 380-400° C. The extrusion speed can be 15-30 mm / min, preferably 20-28 mm / min, and more preferably 20-25 mm / min.

[0053] In some other embodiments, the alloy solution after slagging can be cast into a cast rod, extruded into a thin rod, and then coiled into a coil to obtain a grain refiner. The continuous casting and rolling temperature can be 400-600°C, preferably 450-550°C, and more preferably 480-520°C. The continuous casting and rolling speed can be 1-3 m / min, preferably 1.2-2.5 m / min, and more preferably 1.5-2.0 m / min.

[0054] <Grain refiner>

[0055] The grain refiner of the present invention comprises Ti, B, C, Re and Al. Preferably, the grain refiner of the present invention consists of the aforementioned elements, wherein Re represents a rare earth element.

[0056] The content of Ti may be 3.1 to 4.5 wt %, preferably 3.3 to 4.4 wt %, and more preferably 3.4 to 4.0 wt %.

[0057] The content of B may be 0.41 to 2.0 wt %, preferably 0.42 to 1.0 wt %, and more preferably 0.42 to 0.8 wt %.

[0058] The content of C may be 0.01 to 0.2 wt %, preferably 0.05 to 0.15 wt %, and more preferably 0.08 to 0.13 wt %.

[0059] The content of Re may be 0.2 to 1.5 wt %, preferably 0.4 to 1.2 wt %, and more preferably 0.5 to 1.1 wt %.

[0060] The alloy nucleation particle phase of the grain refiner of the present invention includes TiAl3 phase, C-doped TiB2, B-doped TiC phase and Ti2Al 20 One or more RE phases, the matrix phase is α-Al phase.

[0061] The size of the TiAl3 phase is less than or equal to 20 μm, preferably less than or equal to 10 μm; the size of the C-doped TiB2 phase is less than or equal to 1 μm, preferably less than or equal to 0.5 μm; the size of the B-doped TiC phase is less than or equal to 1 μm, preferably less than or equal to 0.5 μm; the size of the Ti2Al 20 The size of the RE phase is 10 μm or less, preferably 5 μm or less.

[0062] <Method for preparing aluminum material>

[0063] The present invention also provides a method for preparing an aluminum material, comprising the following steps:

[0064] The aluminum raw material is melted to obtain an aluminum melt; the grain refiner is added to the aluminum melt to obtain a molten metal; the molten metal is refined, degassed, and slag-removed, then cooled, and then solidified and formed to obtain a refined aluminum material.

[0065] In some embodiments, the aluminum material is pure aluminum, and in other embodiments, the aluminum material is an aluminum-silicon alloy; wherein the silicon content in the aluminum-silicon alloy is greater than or equal to 5wt%, for example, may be 7wt%.

[0066] The refining agent may be those known in the art, for example, the refining agent may be selected from 25% Na3SiF6-12.5% ​​KCl-62.5% NaCl, 10% Na3AlF6-10% KCl-50% NaCl-30% NaF, or 15% Na3AlF6-45% NaCl-40% NaF.

[0067] In the present invention, the grain refiner may be added in an amount of 0.05-0.6% of the mass of the aluminum melt; preferably, the grain refiner is added in an amount of 0.10-0.5% of the mass of the aluminum melt; more preferably, the grain refiner is added in an amount of 0.10-0.3% of the mass of the aluminum melt.

[0068] <Aluminum Material>

[0069] The aluminum material of the present invention is prepared by the above method. The grain size of the aluminum material prepared by the method of the present invention can be refined to less than 90 μm; preferably, it can be refined to less than 80 μm.

[0070] <Purpose>

[0071] The present invention also provides the use of the grain refiner in refining the grain size of aluminum or aluminum alloy. The aluminum alloy can be an aluminum silicon alloy. The composition of the aluminum silicon alloy is specifically as described above, and will not be repeated here.

[0072] <Analysis Method>

[0073] Elemental analysis: Analyzed using Japan Shimadzu ICPS-8100 inductively coupled plasma spectrometer;

[0074] SEM analysis: German Zeiss SIGMA500 was used for microstructure analysis;

[0075] XRD analysis: The phase composition analysis was performed using a Bruker AXSD8 X-ray diffractometer produced by Bruker, Germany;

[0076] Metallographic structure analysis: Zeiss metallographic microscope Axio Imager 2 was used for structure observation and analysis;

[0077] Grain size measurement: According to the metal average grain size standard (GB / T 6394-2017)-intercept point method, the grain size was measured using the metallographic image analysis software AON-STUDIO.

[0078] Example 1

[0079] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa at 10 ° C / min to 800 ° C, keep warm for 30 minutes to form carbon-containing alumina powder (carbon content is about 25%); 200g cryolite, 35g sodium chloride and 37g potassium chloride are placed in a graphite crucible and heated to form a salt solvent melt.

[0080] 15 g of lanthanum oxide, 30 g of cerium oxide and 15 g of carbon-containing aluminum oxide powder were added to 40 g of salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture was cooled to obtain a precursor.

[0081] 944 g of aluminum ingot was formed into aluminum melt, and the temperature of the aluminum melt was controlled at 900° C. 200 g of potassium fluorotitanate and 64 g of potassium fluoroborate were added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate were completely melted, 27 g of precursor was added. After the precursor was completely melted, the reaction was continued with stirring to remove the salt solvent melt, and an alloy solution was obtained.

[0082] The alloy solution is refined, degassed, and slag-stripped in sequence, and then cooled to 730°C and cast into cast rods. The cast rods are hot-extruded into thin rods with a diameter of 9.5 mm, and then coiled; wherein the continuous casting and rolling temperature is 500°C and the speed is 1.5 m / min, and the product grain refiner is obtained.

[0083] Example 2

[0084] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2Pa and heated to 800°C at 10°C / min and kept warm for 30min to form carbon-containing alumina powder; 200g cryolite, 35g sodium chloride and 37g potassium chloride were placed in a graphite crucible and heated to form a salt solvent melt.

[0085] 10 g of lanthanum oxide, 20 g of cerium oxide and 10 g of carbon-containing aluminum oxide powder were added to 60 g of salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture was cooled to obtain a precursor.

[0086] 950g of aluminum ingot was formed into aluminum melt, and the temperature of the aluminum melt was controlled at 900°C. 170g of potassium fluorotitanate and 49g of potassium fluoroborate were added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate were completely melted, 46g of precursor was added. After the precursor was completely melted, the reaction was continued with stirring to remove the salt solvent melt, and an alloy solution was obtained.

[0087] The alloy solution is refined, degassed and deslagging in sequence, then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0088] Example 3

[0089] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa and heated to 800°C at 10°C / min and kept warm for 30min to form carbon-containing alumina powder; 200g cryolite, 35g sodium chloride and 37g potassium chloride were placed in a graphite crucible and heated to form a salt solvent melt.

[0090] 10 g of lanthanum oxide, 20 g of cerium oxide and 20 g of carbon-containing aluminum oxide powder are added to 50 g of salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0091] 954 g of aluminum ingot was formed into aluminum melt, and the temperature of the aluminum melt was controlled at 900° C. 178 g of potassium fluorotitanate and 51 g of potassium fluoroborate were added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate were completely melted, 20 g of precursor was added. After the precursor was completely melted, the reaction was continued with stirring to remove the salt solvent melt, and an alloy solution was obtained.

[0092] The alloy solution is refined, degassed, and slag-stripped in sequence, and then cooled to 730°C and cast into a cast rod. The cast rod is hot-extruded into a thin rod with a diameter of 9.5 mm; wherein the extrusion temperature is 400°C and the extrusion speed is 20 mm / min, and a product grain refiner is obtained.

[0093] Example 4

[0094] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10-2 Pa and heated to 800°C at 10°C / min and kept warm for 30min to form carbon-containing alumina powder; 200g cryolite, 35g sodium chloride and 37g potassium chloride were placed in a graphite crucible and heated to form a salt solvent melt.

[0095] 15 g of lanthanum oxide and 10 g of carbon-containing aluminum oxide powder are added to 75 g of salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0096] 945g of aluminum ingot was formed into aluminum melt, and the temperature of the aluminum melt was controlled at 900°C. 213g of potassium fluorotitanate and 63g of potassium fluoroborate were added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate were completely melted, 45g of precursor was added. After the precursor was completely melted, the reaction was continued with stirring to remove the salt solvent melt, and an alloy solution was obtained.

[0097] The alloy solution is refined, degassed and deslagging in sequence, then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0098] The chemical composition of the grain refiners obtained in Examples 1 to 4 was detected and analyzed using an inductively coupled plasma spectrometer ICP. The detection results are shown in Table 1.

[0099] Table 1

[0100]

[0101] The XRD results of Example 1 and Example 2 are shown in Figure 1 .from Figure 1 It can be seen that the Al-Ti-BC-RE grain refiner is mainly composed of α-Al phase, TiB2 phase, TiC phase, TiAl3 phase and Ti2Al 20 LaCe phase composition.

[0102] The morphology of the C-doped TiB2 phase in the Al-Ti-BC-LaCe grain refiner of Example 1 is shown in FIG. Figure 2a .from Figure 2a to 2c It can be seen that the TiB2 phase particles in the Al-Ti-BC-LaCe grain refiner are relatively small, about 400 nm, and there is C element enrichment on the surface, which hinders its growth and agglomeration.

[0103] The morphology of the B-doped TiC phase in the Al-Ti-BC-LaCe grain refiner of Example 1 is shown in FIG. Figure 3a .from Figure 3a to 3c It can be seen that the TiC particles in the Al-Ti-BC-LaCe grain refiner are relatively small, about 200 nm, and the surface is enriched with B element, which hinders its growth.

[0104] The SEM scanning electron microscope image of Example 1 is shown in Figure 4 .from Figure 4 It can be seen that the Al-Ti-BC-RE alloy microstructure prepared in Example 1 has gray blocky TiAl3 phase with an average size of less than 20 μm; bright white Ti2Al 20 The RE phase is distributed around the TiAl3 phase and on the matrix, with an average size of less than 5μm. There are also fine and dispersed C-doped TiB2 phase and B-doped TiC phase in the matrix, with an average size of less than 0.5μm.

[0105] Comparative Example 1

[0106] Aluminum citrate (C6H5AlO7) was placed in a quartz container and vacuumed to 10 -2 Pa and heated to 800°C at 10°C / min and kept warm for 30min to form carbon-containing alumina powder; 200g cryolite, 35g sodium chloride and 37g potassium chloride were placed in a graphite crucible and heated to form a salt solvent melt.

[0107] 10 g of carbon-containing aluminum oxide powder is added into the salt solvent melt, stirred and mixed to form a liquid-solid mixture, and the liquid-solid mixture is cooled to obtain a precursor.

[0108] 945g of aluminum ingot was formed into aluminum melt, and the temperature of the aluminum melt was controlled at 900°C. 213g of potassium fluorotitanate and 63g of potassium fluoroborate were added to the aluminum melt in batches and stirred. After the potassium fluorotitanate and potassium fluoroborate were completely melted, 45g of precursor was added. After the precursor was completely melted, the reaction was continued with stirring to remove the salt solvent melt, and an alloy solution was obtained.

[0109] The alloy solution is refined, degassed and deslagging in sequence, then cooled to 730°C and cast into ingots to obtain a product grain refiner.

[0110] Experimental Example 1

[0111] The aluminum raw material is melted to obtain an aluminum melt; the grain refiner prepared in Example 1 is added to the aluminum melt and mixed evenly to obtain a metal melt; a refining agent is added to the metal melt, and argon gas is introduced into the metal melt for degassing for 5 minutes by a degasser, and then the slag is removed, and then the temperature is lowered to 720°C, and solidification molding is performed to obtain refined aluminum (also referred to as aluminum material). The mass of the grain refiner added is 0.1% of the mass of the aluminum melt.

[0112] Experimental Example 2

[0113] The difference from Experimental Example 1 is that the grain refiner prepared in Example 2 is used.

[0114] Experimental Example 3

[0115] The difference from Experimental Example 1 is that the grain refiner prepared in Example 3 is used.

[0116] Experimental Example 4

[0117] The difference from Experimental Example 1 is that the grain refiner prepared in Example 4 is used.

[0118] Experimental Example 5

[0119] The difference from Experimental Example 1 is that the aluminum raw material is replaced by aluminum silicon alloy (Al-7Si), and the mass of the grain refiner added is 0.5% of the mass of the aluminum silicon melt.

[0120] Comparative Experiment Example 1

[0121] The difference from Experimental Example 1 is that the grain refiner prepared in Comparative Example 1 is used.

[0122] The metallographic structures of the aluminum raw material and the refined aluminum obtained in Experimental Examples 1 to 4 and Comparative Experimental Example 1 are shown in Figure 5 (a, b, c, d, e, f in order) The grain size of aluminum after being refined by the grain refiner obtained in the example of the present application is significantly reduced.

[0123] The grain size measurement results of the aluminum raw material, the refined aluminum obtained in Experimental Examples 1 to 4 and Comparative Experimental Example 1 are shown in Table 2.

[0124] Table 2

[0125]

[0126] As can be seen from Table 2, the grain size of blank aluminum (i.e., unrefined aluminum raw material) is 486.1 μm. However, the grain size of aluminum refined by the grain refiner of the present invention can be reduced to about 80 μm. Although the grain size of aluminum refined by the grain refiner of Comparative Experimental Example 1 has a certain refining effect, the effect is not as good as that of the grain refiner of the present invention.

[0127] The grain size of the unrefined aluminum-silicon alloy is 176.46 μm, and the grain size of the refined aluminum-silicon alloy obtained in Experimental Example 5 is 77.78 μm. The metallographic structure diagram of the refined aluminum-silicon alloy obtained in Experimental Example 5 is shown in Figure 6 b. From Figure 6 a and Figure 6 b It can be seen that after being refined by the refiner, the structure is transformed from coarse diameter to fine equiaxed crystals, indicating that the Al-Ti-BC-RE refiner prepared in this application has a strong grain refining effect on the Al-7Si alloy, solving the "Si poisoning" problem of the traditional Al-Ti-B refiner.

[0128] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing a grain refiner, characterized in that: The steps include: (1) adding 10 to 60 parts by weight of rare earth oxide and 5 to 30 parts by weight of carbon-containing aluminum oxide powder to 30 to 80 parts by weight of a salt solvent melt, stirring to form a liquid-solid mixture; cooling the liquid-solid mixture to obtain a precursor; (2) 900 to 1000 parts by weight of an aluminum ingot is formed into an aluminum melt; 150 to 250 parts by weight of potassium fluorotitanate and 40 to 70 parts by weight of potassium fluoroborate are added to the aluminum melt and stirred, and then 20 to 50 parts by weight of the precursor obtained in step (1) are added, and the reaction is continued to be stirred until the reaction is complete, and the salt solvent melt is removed to obtain an alloy solution; (3) The alloy solution is refined, degassed and deslagging is performed in sequence to obtain a deslagging alloy solution, and the deslagging alloy solution is molded to obtain a grain refiner.

2. The preparation method according to claim 1, characterized in that: The rare earth element in the rare earth oxide is selected from one or more of lanthanum, cerium, yttrium, erbium and scandium.

3. The preparation method according to claim 1, characterized in that: The salt solvent melt is prepared by heating cryolite, sodium chloride and potassium chloride; wherein, based on the mass of the salt solvent melt, the content of cryolite is 65-85wt%, the content of sodium chloride is 8-15wt%, and the content of potassium chloride is 10-15wt%.

4. The preparation method according to claim 1, characterized in that: Aluminum citrate was placed in a vacuum -2 The temperature is heated to 750-850°C at a heating rate of 8-15°C / min under Pa and kept at this temperature for 20-60 minutes to form carbon-containing alumina powder.

5. The preparation method according to claim 1, characterized in that: The alloy nucleation particle phase of the grain refiner includes TiAl3 phase, C-doped TiB2, B-doped TiC phase and Ti2Al 20 One or more RE phases, the matrix phase is α-Al phase.

6. The preparation method according to claim 5, characterized in that: The size of the TiAl3 phase is less than or equal to 20 μm; the size of the C-doped TiB2 phase is less than or equal to 1 μm, the size of the B-doped TiC phase is less than or equal to 1 μm, and the Ti2Al 20 The size of the RE phase is less than or equal to 10 μm.

7. A grain refiner, characterized in that: It is prepared by the method described in any one of claims 1 to 6.

8. A method for preparing an aluminum material, characterized in that: The steps include: Melting aluminum raw material or aluminum-silicon alloy to obtain a melt; adding the grain refiner according to claim 7 to the melt to obtain a molten metal; refining, degassing and slagging the molten metal, then cooling it, and then performing a solidification molding process to obtain an aluminum material; Wherein, the addition amount of the grain refiner is 0.05-0.6% of the melt mass.

9. An aluminum material, characterized in that: It is prepared by the preparation method described in claim 8.

10. Use of the grain refiner according to claim 7 for refining the grain size of aluminum or its alloys.

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